Polyurethane resins are mainly used in various fields of products for daily life, including automobile upholstery, furniture, materials for electrical devices, and the like, for their characteristics of being low cost, lightweight, and easy to shape. Regarding embodiments of uses, much polyurethane resins are often used as polyurethane foams. However, polyurethane foams, which are polymeric organic compounds, are flammable and may possibly cause an uncontrollable combustion once ignited. A fire caused in a living environment may lead to disaster affecting people's lives. From this point of view, the polyurethane foam production industry has made efforts to avoid fires by introducing flame retardation technology into the foams. Today, depending on the field of applications, parts of the products formed of polyurethane foams, including automobile upholstery, furniture, materials for electrical devices, and the like, are legally required to be flame retardant. Such legal regulations are provided by, for example, the UL Standards for electric products and the MVSS-302 for automobiles in the United States.
Accordingly, flame retardants to impart flame retardance to a polyurethane resin have been developed. However, for a polyurethane resin, in particular, a polyurethane foam, since the required performances are different from other resin products and special, normal flame retardants for general resins are not suitable for a polyurethane resin, in particular, a polyurethane foam.
As flame retardants for a polyurethane foam, halogen-containing flame retardants are widely used.
As examples of halogen-containing flame retardants for a polyurethane foam, tetrakis(2-chloroethyl)ethylene diphosphate (Patent Document 1), 2,2-bis(chloromethyl)-1,3-propylene-bis[bis(2-chloroethyl)phosphate] (Patent Document 2), tris[di(2-chloroethoxy)phosphinyl(dimethyl)methyl]phosphate, 2-chloroethyl bis[di(2-chloroethoxy)phosphinyl(dimethyl)methyl]phosphate (Patent Document 3), oxydi-2,1-ethanediyl tetrakis(2-chloro-1-methylethyl)phosphate (Patent Document 4), and the like have been investigated to date. While halogen-based flame retardants have excellent performances, they contain a halogen element including chlorine, bromine, or the like. Thus, there is a problem that when a product of a polyurethane foam containing such a flame retardant is discarded and then incinerated, a hydrogen halide is generated. The hydrogen halide is an environmental load substance. Moreover, regarding some halogen-based flame retardants, there is a problem that halogenated dioxin or the like is generated. The halogenated dioxin or the like is amore harmful environmental load substance.
Accordingly, it is desired to develop an environment-friendly non-halogen-based flame retardant. However, the present state is that a comprehensively satisfactory flame retardant in points including flame retardance, anti-fogging characteristics, distortion characteristic, scorch characteristic, and the like is not present to date, and development of it is widely desired.
Further, for urethane elastomers, those elastomers having excellent flame retardance also have been desired.